營養(yǎng)級聯效應是理解群落結構和生態(tài)系統(tǒng)功能的基礎,。前期研究表明,，在典型的三級食物鏈中,，牧食食物網中的捕食者能通過減少獵物數量或改變其行為而促進植物生長，即捕食者的“綠色世界”效應(Green-world effect),；而碎屑食物網中的捕食者則通過減少分解者數量,、降低土壤養(yǎng)分有效性,、從而抑制植物生長，表現出“灰色世界”效應(Brown-world effect),。
中科院成都生物研究所孫書存研究員課題組趙川博士等在青藏高原東部典型的高寒草甸,，通過野外微宇宙控制試驗，模擬構建土壤有機質→蚯蚓→步甲三級食物鏈,，研究了土壤食物網中捕食者誘導的營養(yǎng)級聯效應及其生態(tài)系統(tǒng)功能,。研究發(fā)現：步甲并沒有改變蚯蚓的數量，而是迫使蚯蚓向深層土壤轉移,，從而間接地提高了下層土壤的孔隙度和有效養(yǎng)分含量,，并最終增加了植物地上生物量。該結果表明,，碎屑食物網中的捕食者可以通過改變獵物的行為特征而促進植物生長,。這一結果與生態(tài)學傳統(tǒng)理論的預測相反，揭示了捕食者影響植物生長的一種新機制,。
該研究結果已發(fā)表于動物學研究領域的期刊Journal of Animal Ecology,。
該研究得到了國家自然科學基金和全球變化重大研究計劃項目的資助。（生物谷 Bioon.com）
生物谷推薦的英文內容
Journal of Animal Ecology DOI: 10.1111/1365-2656.12058
Predatory beetles facilitate plant growth by driving earthworms to lower soil layers
Chuan Zhao1, John N. Griffin2, Xinwei Wu3, Shucun Sun1,3,*
1. Theory suggests that predators of soil-improving, plant-facilitating detritivores (e.g. earthworms) should suppress plant growth via a negative tri-trophic cascade, but the empirical evidence is still largely lacking.
2. We tested this prediction in an alpine meadow on the Tibetan Plateau by manipulating predatory beetles (presence/absence) and quantifying (i) direct effects on the density and behaviour of earthworms; and (ii) indirect effects on soil properties and above-ground plant biomass.
3. In the absence of predators, earthworms improved soil properties, but did not significantly affect plant biomass. Surprisingly, the presence of predators strengthened the positive effect of earthworms on soil properties leading to the emergence of a positive indirect effect of predators on plant biomass.
4. We attribute this counterintuitive result to: (i) the inability of predators to suppress overall earthworm density; and (ii) the predator-induced earthworm habitat shift from the upper to lower soil layer that enhanced their soil-modifying, plant-facilitating, effects.
5. Our results reveal that plant-level consequences of predators as transmitted through detritivores can hinge on behaviour-mediated indirect interactions that have the potential to overturn predictions based solely on trophic interactions.
6. This work calls for a closer examination of the effects of predators in detritus food webs and the development of spatially explicit theory capable of predicting the occurrence and consequences of predator-induced detritivore behavioural shifts.
